Rod core choke for suppressor application in phase-gating circuits

ABSTRACT

A choke structure employing a rod-type core, for suppressor application in phase-gating circuits with controlled semiconductor components, in which the core comprises laminae of standard construction in the electrical engineering art and additional laminae constructed of deep-drawing quality sheet metal, disposed to form a flux shunt, by means of which at least a part of the magnetic flux otherwise closing through air is constrained to follow a magnetic circuit containing virtually no air gap.

United States Patent [1 1 Wimmer [4 1 Sept. 16, 1975 [54] ROD CORE CHOKE FOR SUPPRESSOR 2,602,097 7/1952 Muller 336/234 X APPLICATION IN PHASE GATING 3,129,399 4/1964 Hansen 336/212 CIRCUITS 3,748,618 7/1973 Kaiserwerth et a1 336/212 [75] Inventor: Josef Wimmer, Wenzenbach, FOREIGN PATENTS 0R APPLICATIONS Germany 260,731 11 /1926 United Kingdom 336/83 880,815 10/1961 United Kingdom 336/83 [73] Assignee: Siemens Aktiengesellschaft, Berlin & 1,024,166 2/1958 Germany 336/212 Munich, Germany 677,23] 11/1964 Italy 336/212 Primary ExaminerThomas J. Kozma Attorney, Agent, or Firm-Hill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson [57 ABSTRACT A choke structure employing a rod-type core, for suppressor application in phase-gating circuits with controlled semiconductor components, in which the core comprises laminae of standard construction in the electrical engineering art and additional laminae constructed of deep-drawing quality sheet metal, disposed to form a flux shunt, by means of which at least a part of the magnetic flux otherwise closing through air is constrained to follow a magnetic circuit containing virtually no air gap.

4 Claims, 7 Drawing Figures ROD CORE CHOKE FOR SUPPRESSOR APPLICATION IN PI-IASE-GATING CIRCUITS BACKGROUND OF THE INVENTION The invention is directed to a rod-core choke for suppressor application in phase-gating circuits with controlled semiconductor components, in which the choke consists of a coil or winding and a cooperable'rod-core utilizing laminae of standard construction in accordance with electrical engineering techniques.

Radio suppressor chokes for damping pulse-type parasitic voltages, of the kind occurring in phase-gating circuits, are known, for example from German Gebrauchsmuster 7,043,934 and 7,1 15,756, in which the cores consist of at least two annular core sections stacked axially one upon the other, with one core section being made of magnetizable iron laminae and the other core section comprising a ferrite core. The ferrite ring thus formed possibly may contain an air gap. In this context, the laminae section of the core can be constructed equally as well of deep-drawing quality sheet metal.

Investigations have shown that the known rod-core chokes are suitable as suppressor components with respect to specific power levels which are being regulated, but at low power levels such chokes are unsuitable. These problems, among others, are dealt with in the magazine Siemens-Bauteile-Informationen" 8th year of edition I970), Special Edition entitled Radio Suppressors, pages 12 to 15.

The invention is directed to the modification of known rod-core chokes in such a manner that their low cost of manufacture is retained, but the coil properties are so altered by skillful modification, that the operating range of the phase-gating circuit to which suppression is being applied can be extended to include lower power levels, enabling regulation thereof without disturbance.

SUMMARY OF THE INVENTION In accordance with the invention, this objective is achieved by the utilization of additional laminae constructed of deep-drawing quality sheet metal, by means of at least a part of the magnetic flux otherwise closing through air, is constrained to follow a magnetic circuit containing virtually no air gap.

Deep-drawing quality sheet metal has the advantages that it has higher magnetic losses than laminae constructed in accordance with standard electrical engineering, that it exhibits a less marked magnetostriction, so that the inherent noise of the choke is reduced, and that it can be easily worked, in particular, easily bent. Further, rod-core chokes are inherently substantially simpler to manufacture than ring-core chokes.

Advantageously, the additional laminae employing deep-drawing quality sheet metal may have a U-shaped configuration with relatively long legs, and when inserted into the coil will replace a corresponding number of laminae of standard construction. In this context, the U-shaped laminae are inserted in the coil either from one end only or alternately from both ends. In the embodiment in which they are inserted from both ends, they can be welded together, i.e., spot-welded at overlapping portions so that the mechanical strength of the choke is increased. It is also possible to stamp out the additional laminae in planar form, of U-shaped configuration, with relatively long legs and relatively short bases and to insert them edgewise into the coil so that a corresponding number of standard laminae are replaced. Preferably, the additional laminae may have a U-shaped configuration in longitudinal cross-section, with relatively short legs and a relatively long base, which may be slid externally over the coil which is, in this case, packed with standard laminae. In this embodiment, therefore, the choke is manufactured in a conventional manner and thereafter modified to accord with the desired special application. It has been found that the range of disturbance-free operation can be readily adjusted by variation in the number employed of additional U-shaped laminae of deep-drawin g quality.

The last-mentioned embodiment may also be modified by employing planar laminae having a U-shaped configuration with relatively short legs and relatively long bases which are slid on edge over a coil packed with laminae of standard construction, the additional laminae in this construction thus being rotated through with respect to those previously described.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, wherein like reference characters indicate like or corresponding elements,

FIG. 1 schematically illustrates a typical phase-gating circuit employing a controlled semiconductor and suppression facility;

FIG. 2 is a longitudinal section through a suppressor choke with rodtype core, illustrating the application of the present invention thereto;

FIG. 3 is a sectional view similar to FIG. 2 illustrating a further modification of the invention;

FIG. 4 is a side elevational view of a choke embodying still another modification of the invention;

FIG. 5 is an end elevational view of the structure illustrated in FIG. 4;

FIG. 6 is a side elevational view similar to FIG. 4 illustrating a further modification of the invention; and

FIG. 7 is a side elevational view of the construction illustrated in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, there is schematically illustrated, a typical phase-gating circuit employing a controlled semiconductor component and suppression facility. The current from the AC voltage source V, flows through the controlled semiconductor H and the suppressor choke L, to the load R and from there back to the voltage source. An additional suppressor action is here achieved by the utilization of a capacitor C. As long as the semiconductor component H is in a highresistance state, the capacitor C will charge. and when the semiconductor component I-I switches to a lowresistance state, the capacitor C will discharge across the coil L, so that an oscillatory circuit is created whose current flows through the semiconductor component H in addition to the main or power current, as a result of which known types of disturbances can result. Such disturbances become more probable as the main current flowing through the load becomes smaller in relation to the compensating current, which remains the same and is determined by the components L and C.

By the introduction of a choke constructed in accordance with the invention, it is possible to materially restrict the effect of such compensating current, so that even at small main currents, i.e., when the load power 3 is low, disturbance-free operation of the overall circuit is insured.

Referring to FIG. 2, the choke coil 1, having external connections 4, has the central hole or bore thereof partially packed with laminae 2 of standard electrical construction. In addition thereto, a lamina 3, constructed of deep-drawing quality sheet metal, and of U-shape in longitudinal cross-section, is provided, such lamina 3 having a pair of relatively long legs and a relatively short base. The lamina 3 has one of its long legs inserted in the central bore of the coil, thus replacing one of the standard laminae otherwise employed, with the free leg being disposed adjacent the outer face of the coil. It will be apparent that with such construction the magnetic flux 5, which would otherwise close through air, is forced to follow a magnetic circuit containing only a small air gap. Several such additional laminae 3 can also be employed.

By the introduction of core-laminae of this type, to a choke employed in a circuit of the type illustrated in FIG. 1, and designed for a rated power of 220 W, the disturbance-free controllable minimum power of 125 W could be reduced to 100 W when using one such additional lamina and to 60 W when using five such laminae.

FIG. 3 illustrates another embodiment, in which two additional U-shaped laminae 3 are inserted "into the core, one from each end, the outermost legs 3 of which may be spot-welded, as indicated at 6, thereby rigidly securing the core laminae in assembled relation. The controllable minimum load achievable with an embodiment of this type, utilizing a total of only two additional laminae was 85 W.

In the construction illustrated in FIGS. 4 and 5, additional laminae, of U-shaped configuration in longitudinal cross-section, are employed. Such laminae are provided with relatively short legs and relatively long bases which are slipped over the completed rodcorc choke, whereby the respective legs of such additional laminae are disposed adjacent the ends of the standard laminae 2. Likewise, where more than a single additional lamina 3 is employed, the latter may be designed to nest one within the other as illustrated in FIGS. 4 and 5. Here, again, by means of a suitable selection of the number of additional laminae 3 to be employed, variations in the desired electrical properties can be achieved. In this construction, when utilizing a single lamina 3, the disturbance-free controllable minimum power is 93 W,

when using three laminae it is W, 40 W for five laminae and 25 W for nine such laminae.

In the construction illustrated in FIGS. 6 and 7, the additional laminae are likewise of U-shaped configuration, employing relatively short legs and relatively long bases, but in this case the laminations are of planar form, for example, punched from flat stock and are assembled in side-by-side relation, i.e., rotated through as compared with the relationship illustrated in the embodiment of FIGS. 4 and 5.

It will be appreciated from the above that by utilization of the described measures, it is possible in accordance with the invention to substantially increase the disturbance-free controllable load range of rod-type suppressor chokes, employing one in the same choke size, without impairment of the legally imposed suppressor action.

Having thus described my invention, it will be obvious that although minor modifications might be suggested by those first in the art, it should be understood that I wish to embody within the scope of the patent warranted herein all such modifications as reasonably and profitably come within the scope of my contribution to the art.

I claim as my invention:

1. In a choke employing a rod-type core, for suppressor applications in phase-gating circuits with controlled semiconductor components, the combination of a coil and a plurality of flat, elongated rectangular-shaped laminae disposed in alignment in side by side relation to form a rod-type core, at least one additional lamina, constructed of deep-drawing quality sheet metal, which additional lamina is of U-shaped configuration with relatively long legs and a relatively short base, one leg of which is inserted into the choke coil, taking the place of a corresponding first-mentioned rectangular-shaped lamina, to form a flux shunt, by means of which at least part of the magnetic flux otherwise closing through air, is forced in an almost air-gap-free magnetic loop.

2. A choke according to claim 1, wherein the deepdrawing quality lamina is inserted into the coil from one end only.

3. A choke according to claim 1, wherein the deepdrawing quality laminae are alternately inserted into the coil from both ends.

4. A choke according to claim 3, wherein the individ ual additional laminae are welded together. 

1. In a choke employing a rod-type core, for suppressor applications in phase-gating circuits with controlled semiconductor components, the combination of a coil and a plurality of flat, elongated rectangular-shaped laminae disposed in alignment in side by side relation to form a rod-type core, at least one additional lamiNa, constructed of deep-drawing quality sheet metal, which additional lamina is of U-shaped configuration with relatively long legs and a relatively short base, one leg of which is inserted into the choke coil, taking the place of a corresponding first-mentioned rectangular-shaped lamina, to form a flux shunt, by means of which at least part of the magnetic flux otherwise closing through air, is forced in an almost airgap-free magnetic loop.
 2. A choke according to claim 1, wherein the deepdrawing quality lamina is inserted into the coil from one end only.
 3. A choke according to claim 1, wherein the deepdrawing quality laminae are alternately inserted into the coil from both ends.
 4. A choke according to claim 3, wherein the individual additional laminae are welded together. 